1. Field of the Invention
This invention relates to a reservoir technique for supplying a working fluid to a master cylinder of vehicles, and more particularly to a reservoir of the type which comprises an auxiliary reservoir located proximal or close to a master cylinder and a main reservoir having a hydraulic fluid inlet opening and connected to the auxiliary reservoir through a piping.
2. Related Art
A master cylinder of vehicles essentially requires a working fluid for operating the braking system, etc. It is the reservoir apparatus which stores the working fluid. Experience teaches that work is also necessary for supplying a working fluid to the reservoir apparatus or replacing the working fluid with new one.
There is known a reservoir apparatus which has been developed taking into consideration the replenishing work and replacing work of the working fluid and in which a hydraulic fluid inlet opening for the working fluid is arranged at a located where both the replenishing work and the replacing work can easily be made. For example, as shown in a microfilm (first example of the related art) of Japanese Utility Model Application No. S56-14365 (Japanese Utility Model Application Unexamined Publication No. S58-48555), the reservoir apparatus is divided into an auxiliary reservoir and a main reservoir, both of the reservoirs are connected to each other through a piping such as a hose or the like, and an inlet opening for feeding a hydraulic fluid is arranged at a location where it does not interfere other devices (in other words, at a location easy to work). This conventional invention is based on an idea that the auxiliary reservoir is arranged at a location proximal to a master cylinder so that a working fluid can be supplied to the master cylinder rapidly and smoothly, while the other main reservoir is provided with a hydraulic fluid inlet opening and arranged at a location where a hydraulic fluid can easily be supplied therein. According to this idea, the incompatible requirements for installing the master cylinder in a limited space together with other devices and for enabling the replenishment or replacement of the working fluid with ease can be satisfied at the same time.
According to the technique shown in the first example of the related art, the connecting portion of the piping on the auxiliary reservoir side located proximate to the master cylinder is disposed in an upright posture on an upper part of the auxiliary reservoir. However, in that form, the height of the auxiliary reservoir on the master cylinder becomes high as a whole and the mounting space of the master cylinder with the auxiliary reservoir attached thereto becomes large. In order to reduce the mounting space, the connecting portion of the piping is, as disclosed in Japanese Utility Model Publication No. H08-2007 (second example of the related art), preferably slanted with respect to a direction of the height of the auxiliary reservoir.
3. Problems to be Solved
The inventor of the present invention paid attention to the technique for diagonally drawing out the connecting portion of the pining or the connecting pipe for connecting the piping from the upper part of the auxiliary reservoir and carried out an extensive experiment and study about replenishment property of the working fluid into the auxiliary reservoir. As a result, he found out a fact that a film of the working fluid is formed at an opening portion of the connecting pipe which faces the inside of the auxiliary reservoir at the time of replenishment and therefore, there is such a risk that the film jeopardizes the replenishment property of the working fluid. Incidentally, the replenishment of the working fluid into the auxiliary reservoir is conducted in such a manner that the working fluid is supplied from the hydraulic fluid inlet port of the main reservoir and replaced with air in the auxiliary reservoir through the piping. Accordingly, when the working fluid flows from the main reservoir side towards the auxiliary reservoir side, the air in the auxiliary reservoir (i.e., air to be replaced with the working fluid) flows from the auxiliary reservoir side towards the main reservoir side. As a method for preventing the formation of the film which covers the opening portion, it can also be considered that the inside of the auxiliary reservoir is evacuated or reduced in pressure, i.e., the method of vacuum breathing is applied. However, it is required for vacuum breathing to employ extra equipment such as a vacuum pump and in addition, the operation is troublesome. In this respect, the method for replacing the atmospheric air on the auxiliary reservoir side with the working fluid from the main reservoir side does not require extra devices and the operation is easy.
It is, therefore, an object of the present invention to provide a technique capable of replenishing a working fluid smoothly while employing a method for replacing an atmospheric air with the working fluid.
It is another object of the present invention to provide a technique capable of enhancing the replenishment property of a working fluid merely by slightly changing the configuration or constitution of an auxiliary reservoir located proximal to a master cylinder.
Other objects of the present invention will become more clear from the following description.
When the air in an auxiliary reservoir is replaced with a working fluid, the working fluid which flows into the auxiliary reservoir from an opening portion of a connecting pipe is affected by the air flowing from the auxiliary reservoir side towards the main reservoir side (flow reverse to the flow of the working fluid). Probably, the air forms a film, i.e., the so-called xe2x80x9csoap bubblexe2x80x9d, covering the opening portion using the viscous working fluid as a xe2x80x9csoap bubble liquidxe2x80x9d. The basis of this invention for solving the problems is to provide a constitution in which the film, i.e., xe2x80x9csoap bubblexe2x80x9d covering the opening portion, is difficult to be formed.
Based on such basis, according to this invention, the connecting pipe is provided at its opening portion with a recessed portion and/or protruded portion for changing the configuration of the opening portion. The recessed portion and/or protruded portion used herein refers to a) only recessed portion but the number of the recessed portion is not limited to one, b) only protruded portion but the number of the protruded portion is not limited to one, and c) a combination of a) and b). The auxiliary reservoir including the connecting pipe is usually a molded article from synthetic resin. The recessed portion and/or protruded portion can easily be formed by molding.
The form for preventing the generation of the film which covers the opening portion is preferably a recessed portion disposed at a lower side of the opening portion, and particularly preferably a recessed portion extending downward when viewed in a direction of the height of the auxiliary reservoir, one end of the recessed portion being connected to the inner side of the connecting pipe and the other end of the recessed portion being extended along the inner wall of the auxiliary reservoir from the opening portion and reaching the lower part. The recessed portion of this case has the function for enlarging the size of the opening portion and enhancing a more smooth flow of the replenishment working fluid at the nearby area of the opening portion when compared with a case where there is no such recessed portion. Owing to this function of the recessed portion, it can be considered that the opening portion of the connecting pipe is more enlarged even at the time for replenishment of the working fluid thereby preventing the generation of the film of the working fluid. In contrast, the protruded portion is preferably disposed at an upper part of the opening portion. The protruded portion has the function for defining a plurality of passageways at the upper part of the opening portion thereby dividing the flow of air from the flow of working fluid. Owing to this function of the protruded portion, it can be considered that the effect of the flow of air to be prevailed on the replenishment working fluid becomes so small that no film of the working fluid is formed at the opening portion.
As another form of the protruded portion, the opening portion of the connecting pipe may be disposed in such a manner as to be orthogonal to a direction of the height of the auxiliary reservoir. In that case, the entire opening portion is located at the uppermost part of a reservoir space formed within the auxiliary reservoir. Consequence, as the replenishment working fluid fills the reservoir space in the auxiliary reservoir, the entire opening portion is choked with the working fluid almost at the same time (i.e., instantaneously) on the last stage of the filling operation. Accordingly, it can be consistently avoided that the size of the opening portion of the connecting pipe is gradually reduced. Since it is considered that the film covering the opening portion, i.e., the so-called xe2x80x9csoap bubblexe2x80x9d is generated in a state in which the size of the connecting pipe is gradually reduced, another form of the protruded portion as mentioned is also effective.